Continuous irradiation with a 633-nm light-emitting diode exerts an anti-aging effect on human skin cells.

What the authors concluded

In the present study, we demonstrated that continuous irradiation with a 633±3-nm LED exerted anti-aging effects in both in vitro and ex vivo experiments. More specifically, irradiation with a 633-nm LED for 2 days increased the synthesis of type 1 procollagen and decreased the expression of matrix metalloproteinase (MMP)1 and MMP2 in skin fibroblasts. In addition, irradiation with a 633-nm LED

Devices that emit this wavelength

Matched on wavelength within 15nm, since LED bins vary by roughly that much and a tighter match would be false precision. Where we have an irradiance figure, the session length is the time needed to reach this study's dose of 0.43 J/cm² at that intensity.

Matching a wavelength is not the same as reproducing a trial. Session times assume the device's published irradiance is accurate at the distance it was measured, which on brand-claim figures is often optimistic. Where a device publishes both a peak and an average we use the average, and where it publishes a falloff curve we use the lowest figure, so these times run long rather than short. Clinical protocols also control for spot size, contact and skin type in ways a home device cannot.